Kubota MX4700/5100 question

[loggin]

Hello all! Was wondering if anyone might know what the front to rear axle ratio might be for Kubota MX4700/5100?
Seems like important information that is not contained in the owner's manual. Or at least I have not been able to find it.

 

[5030]

It will be in the WSM but I have to ask why it's important to you?

 

[loggin]

It will be in the WSM but I have to ask why it's important to you?

Thank you for your response!. I did manage to have a look in the shop manual as well and could not find it although I may have missed it. I am considering tire replacements and would like to be able to match rolling circumferences within 4-5 percent of each other front to rear. I believe that is what most manufacturers require but not sure..??

 

[5030]

Actually, it's called 'lead lag' and 4% is acceptable. The WSM should call out all applicable tires sizes (front and rear) for your model. I know my WSM for my M9's does.

If you exceed 4%, tread wear becomes an issue as well as stress on driveline components. Keep in mind that with a FWA tractor, whether the front wheel assist is engaged or not, you are still applying load the internal gearing.

People say that don't apply with a 4 wheel motor vehicle, but it does, especially with an AWD vehicle which is why it's bad pizza to put oversized tires on anything that is AWD, motor vehicle wise....

I probably should add that it's tire circumference that is more important that actual width and radials versus bias, the circumference will vary between the two designs.

 

[loggin]

Actually, it's called 'lead lag' and 4% is acceptable. The WSM should call out all applicable tires sizes (front and rear) for your model. I know my WSM for my M9's does.

If you exceed 4%, tread wear becomes an issue as well as stress on driveline components. Keep in mind that with a FWA tractor, whether the front wheel assist is engaged or not, you are still applying load the internal gearing.

People say that don't apply with a 4 wheel motor vehicle, but it does, especially with an AWD vehicle which is why it's bad pizza to put oversized tires on anything that is AWD, motor vehicle wise....

I probably should add that it's tire circumference that is more important that actual width and radials versus bias, the circumference will vary between the two designs.

Thank you again 5030!! I do see tire sizes in my manual but in my search for tires I have found that tires with the same size figures often have different rolling circumferences. I just don't want to compound a difference between front and rear and be outside of the 4 percent tolerance.

 

[5030]

Do keep in mid that if the unit is FWA, most times the front tire circumference will be smaller than the rear and the internal gear ratio will compensate for that. If the shop manual don't call it out, a call to your dealer should provide that data.

Of course none of that applies with a 2wd unit.

The owners manual may or may not specify but the factory shop manual will and your local dealer will know as well because most tractor manufacturers off varying tire sizes, depending on intended end user application.

When customers buy a new unit (inexperience), they run tires the dealer recommends. In my case, I run what I require to farm with. Consequently, I run R1', either radial or bias with 27 degree drive lugs.

 

[loggin]

Do keep in mid that if the unit is FWA, most times the front tire circumference will be smaller than the rear and the internal gear ratio will compensate for that. If the shop manual don't call it out, a call to your dealer should provide that data.

Of course none of that applies with a 2wd unit.

The owners manual may or may not specify but the factory shop manual will and your local dealer will know as well because most tractor manufacturers off varying tire sizes, depending on intended end user application.

When customers buy a new unit (inexperience), they run tires the dealer recommends. In my case, I run what I require to farm with. Consequently, I run R1', either radial or bias with 27 degree drive lugs.

A call to the dealer is probably in order. Thanks again for your help 5030!!

 

[LD1]

I think you might be overthinking it.

Ag tires for the mx are 9.5-16 fronts and 14.9-26 rears. Just how much variation in rolling circumference are you seeing among different manufactures in those sizes?

Look up the specs for the tires that are actually on the machine.

IF you choose a brand that has that specific size slightly larger in the rear.....try to find a MFG that has slightly larger in the front and NOT slightly smaller.

But I think ANY 9.5 ag tire on the front and ANY 14.9-26 rear can be paired with one another and still be within what is considered acceptable

 

[Hoobie]

I have an MX5100 and went through this too a while back. I contacted Kubota. The gear ratio you are looking for is 1.559. I attached my correspondence which I hope comes through. Never tried attaching before.
There is a formula to use with this ratio to assure you are in the appropriate front lead range.

 

[Jerry/MT]

Actually, it's called 'lead lag' and 4% is acceptable. The WSM should call out all applicable tires sizes (front and rear) for your model. I know my WSM for my M9's does.

If you exceed 4%, tread wear becomes an issue as well as stress on driveline components. Keep in mind that with a FWA tractor, whether the front wheel assist is engaged or not, you are still applying load the internal gearing.

People say that don't apply with a 4 wheel motor vehicle, but it does, especially with an AWD vehicle which is why it's bad pizza to put oversized tires on anything that is AWD, motor vehicle wise....

I probably should add that it's tire circumference that is more important that actual width and radials versus bias, the circumference will vary between the two designs.

"Keep in mind that with a FWA tractor, whether the front wheel assist is engaged or not, you are still applying load the internal gearing."

I don't understand what you mean by this statement. Can you please expand on this?

 

[5030]

Whether the front axle is engaged or not, the driveline is turning all the way into the transmission regardless and imposing a parasitic load. Never seen any tractor with freewheeling front hubs....

Had to replace the front spline coupler on one of my M's last summer because the driveline wore it out, even though I rarely if ever engage the front wheel assist.

M Series use a 2 piece driveshaft with a splined coupler secured to the back driveshaft half with a roll pin. Nothing that a 50 buck part won't cure.

 

[Hoobie]

Whether the front axle is engaged or not, the driveline is turning all the way into the transmission regardless and imposing a parasitic load. Never seen any tractor with freewheeling front hubs....

Had to replace the front spline coupler on one of my M's last summer because the driveline wore it out, even though I rarely if ever engage the front wheel assist.

M Series use a 2 piece driveshaft with a splined coupler secured to the back driveshaft half with a roll pin. Nothing that a 50 buck part won't cure.

Now that is new to me. But when I think about it makes sense. All the linkages from the front are turning all way back to the transmission even when not in FWA. They just aren't pulling. I thought the fronts were just spinning on the hubs.
Have I got it right?

 

[loggin]

I have an MX5100 and went through this too a while back. I contacted Kubota. The gear ratio you are looking for is 1.559. I attached my correspondence which I hope comes through. Never tried attaching before.
There is a formula to use with this ratio to assure you are in the appropriate front lead range.



View attachment 704537

Thank you for the information Hoobie!!

 

[Jerry/MT]

Whether the front axle is engaged or not, the driveline is turning all the way into the transmission regardless and imposing a parasitic load. Never seen any tractor with freewheeling front hubs....

Had to replace the front spline coupler on one of my M's last summer because the driveline wore it out, even though I rarely if ever engage the front wheel assist.

M Series use a 2 piece driveshaft with a splined coupler secured to the back driveshaft half with a roll pin. Nothing that a 50 buck part won't cure.

Thank you. I thought that's what you might mean. Those loads are relatively small as you point out.